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Comment by Balgair | Hacker News Reader

Yall, we're not putting humans on Mars anytime soon.

Okay, okay, rather we're not getting humans back off of Mars anytime soon.

Landing is by far the easy part. MSR was partly a mission to see how hard it really is to get anything back into space from the Martian surface. If you can manage a pound, you can probably then manage 3 or so 180 pound humans and all their safety support.

Like, think of it. You somehow have to land a fully fueled rocket on freaking Mars. No site prep, near vacuum and no aero breaking, very expensive and nearly impossible second chance.

Fine fine, you just land the shell and then refuel on Mars with some form of automated fuel refinery on Mars. Like, if you have robots that can do that, you've ended capitalism already and have no need for humans in the first place.

Im not saying a human return mission is impossible, but it is just so very much harder than a Trillion dollar Apollo program lets us believe.

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You just send a few unmanned missions first with fuel and supplies?

"Supplies" as in, self-assembling landing and launch pads?

People have successfully dropped autonomous robots onto Mars before. Wouldn't be out of the question to do so again, except that instead of rovers, the robots could be programmed to open up crates (dropped at the same time, or by a previous or future mission) and assemble what's inside into a landing or launch pad.

Would take a lot of prep missions, and might not be worth the cost, but in theory it's doable. Curiosity massed 900 kg and Perseverance massed 1025 kg according to Wikipedia, so dropping a metric ton of supplies for the robot to assemble would, again in theory, be feasible. (In practice the equipment for landing the supply crates safely would take up a good chunk of the mass budget, but there should be something left over in the mass budget for the crates to contain).

It would possibly be more practical to store the return trip fuel in orbit around Mars.

Mass-wise, yes, but long term fuel storage and transfer in a vacuum is all completely theoretical at this point

I doubt it would be practical to pump fuel to another rocket. The obvious thing to do is store the fuel in orbit with its own rocket engine. Then you only have to dock with it and turn on the engine.

Solid-state boosters are potentially even better. No boil-off of fuel to worry about

Good idea! Although solid fuel rockets cannot be throttled or turned off.

You still have to land all the fuel to get the people off of Mars

Yes, but that's a lot less fuel than a return trip from Mars.

If you have robots like this, why send humans in the first place then? You've already got the bots that can do pretty much everything a human could want to do and you don't have to get them back off Mars.

Robots specialized in assembling one machine are not general-purpose robots. I doubt they would be able to "do pretty much everything a human could want to do".

Now, if someone does perfect a general-purpose, AI-driven robot, then yes, sending that robot on the Mars mission instead of a human would make a lot of sense. That's kind of, kind of, what we've done already with the rovers. But until such a general-purpose robot is actually created, human beings are still the most versatile, adaptable entities that could go to Mars.

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